A thin film obtained by stacking an ITO thin film and a molybdenum thin film is used as part of an electrical circuit of a liquid crystal display or other electric devices. It is known that, when a molybdenum thin film is deposited on an ITO thin film, internal stress is generated in each of the formed thin films, causing the films to be peeled off or broken.
The internal stress is divided into two stresses; tensile stress and compression stress. Here, the tensile stress is stress generated in a thin film when the deposited film surface is depressed, and the compression stress is stress generated in a thin film when the deposited film surface is projected.
Normally, an ITO film is subjected to compression stress and a metal thin film (especially a molybdenum thin film) is subjected to tensile stress. If a multilayer structure is obtained by stacking these thin films under such stresses, these thin films eventually peel off or are broken since not only the type of stress is different (compression and tensile) but also the degree of difference in stress becomes large between compression stress and tensile stress, thereby causing a significant degree of warping to be generated at the interface.
For the above-mentioned reason, conventional multilayer structures are disadvantageous, since adhesiveness between an ITO thin film and a molybdenum thin film is poor, cracking or breakage of these films occur due to stress generated between the thin films, resulting in increased defectiveness in products and lowered production yield (Patent Document 1).
In order to solve the above-mentioned problem, a method is disclosed in which complicated steps are combined to produce a multilayer film which is free from peeling and breakage. This method is, however, disadvantageous since production yield is lowered due to increased production steps (Patent Document 2).
For example, in a polycrystalline ITO (p-ITO) method, a multilayer body is produced by depositing a p-ITO film using a vacuum sputtering apparatus, etching the resulting ITO film, depositing a film of molybdenum thereon by means of a sputtering apparatus, and etching the resulting molybdenum film. This method is complicated since film deposition and etching are repeated twice, and hence suffers from poor productivity.
Under such circumstances, a technique has been demanded in which the processes of film deposition and etching can be simplified while preventing cracking and breakage of films caused by stress between an ITO thin film and a molybdenum thin film.    Patent Document 1: JP-A-10-253992    Patent Document 2: JP-A-2005-62889
The invention has been made in view of the above-mentioned problem. An object of the invention is to provide a multilayer structure which contributes to a decrease in product defectiveness ascribable to cracking or breakage of wiring materials, as well as to improvement of production yield.
Another object of the invention is to provide a method for producing the above-mentioned multilayer structure.
Still another object of the invention is to provide an electrode for an electrical circuit comprising the above-mentioned multilayer structure.
Further object of the invention is to provide an electric device comprising the above-mentioned multilayer structure or the above-mentioned electrode for an electrical circuit.